Adhesive Compositions, Micro-Fluid Ejection Devices, and Methods for Attaching Micro-Fluid Ejection Heads

ABSTRACT

Adhesive compositions, micro-fluid ejection devices, and methods for attaching micro-fluid ejection heads to devices. One such adhesive composition is provided for use in attaching a micro-fluid ejection head to a device, such as to reduce chip bowing and/or to decrease chip fragility upon curing of the adhesive. Such an exemplary composition may include one having from about 50.0 to about 95.0 percent by weight of at least one cross-linkable resin selected from the group consisting of epoxy resins, siloxane resins, urethane resins, and functionalized olefin resins; from about 0.1 to about 25.0 percent by weight of at least one thermal curative agent; and from about 0.0 to about 30.0 percent by weight filler, and exhibit a relatively low shear modulus upon curing (e.g., less than about 10.0 MPa at 25° C.).

RELATED APPLICATIONS

This application is a continuation of provisional application Ser. No.60/743,920, filed Mar. 29, 2006.

TECHNICAL FIELD

The disclosure relates to adhesive compositions, and in one particularembodiment, to flexible compounds that can be cured for use as adhesivesin micro-fluid ejection devices.

BACKGROUND AND SUMMARY

Micro-fluid ejection heads are useful for ejecting a variety of fluidsincluding inks, cooling fluids, pharmaceuticals, lubricants and thelike. A widely used micro-fluid ejection head is an inkjet print headused in an ink jet printer. Ink jet printers continue to be improved asthe technology for making their micro-fluid ejection heads continues toadvance.

In the production of conventional thermal ink jet print cartridges foruse in ink jet printers, one or more micro-fluid ejection heads aretypically bonded to one or more chip pockets of an ejection devicestructure. A micro-fluid ejection head typically includes afluid-receiving opening and fluid supply channels through which fluidtravels to a plurality of bubble chambers. Each bubble chamber includesan actuator such as a resistor which, when addressed with an energypulse, momentarily vaporizes the fluid and forms a bubble which expels afluid droplet. The micro-fluid ejection head typically comprises anejector chip and a nozzle plate having a plurality of discharge orificesformed therein.

A container, which may be integral with, detachable from or remotelyconnected to (such as by tubing) the ejection device structure, servesas a reservoir for the fluid and includes a fluid supply opening thatcommunicates with a fluid-receiving opening of a micro-fluid ejectionhead for supplying ink to the bubble chambers in the micro-fluidejection head.

During assembly of the micro-fluid ejection head to the ejection devicestructure, an adhesive is used to bond the ejection head to the ejectiondevice structure. The adhesive “fixes” the micro-fluid ejection head tothe ejection device structure such that its location relative to theejection device structure is substantially immovable and does not shiftduring processing or use of the ejection head. The bonding and fixingstep is often referred to as a “die attach step.” Further, the adhesivemay provide additional functions such as serving as a fluid gasketagainst leakage of fluid and as corrosion protection for conductivetracing. The latter function for the adhesive is referred to as part ofthe adhesive's encapsulating function, thereby further defining theadhesive as an “encapsulant” to protect electrical components of or usedwith the micro-fluid ejection head, such as a flexible circuit (e.g., aTAB circuit) attached to the micro-fluid ejection head.

However, the micro-fluid ejection head and the ejection device structuretypically have dissimilar coefficients of thermal expansion. Forexample, micro-fluid ejection heads may have silicon or ceramicsubstrates that are bonded to an ejection device structure that may be apolymeric material such as a modified phenylene oxide. Thus, theadhesive must often accommodate both dissimilar expansions andcontractions of the micro-fluid ejection head and the ejection devicestructure, and be resistant to attack by the ejected fluid.

Conventional adhesive materials tend to be non-flexible and brittleafter curing due to high temperatures required for curing and relativelyhigh shear modulus of the adhesive materials upon curing. Suchproperties may cause the adhesive materials to chip or crack. It mayalso cause the components (e.g., micro-fluid ejection head and/orejection device structure) to bow, chip, crack, or otherwise separatefrom one another, or to be less resilient to external forces (e.g.,chips may be more prone to crack when dropped). For example, during aconventional thennal curing process, the ejection device structuretypically expands before a conventional die bond adhesive material isfully cured. The diebond material thus moves with the expanding devicestructure, wherein the diebond material cures with the device structurein an expanded state. Upon cooling the device structure, the devicestructure contracts and, with a rigid, cured diebond material, induceshigh stress onto the ejection head to cause the aforementioned bowing,chipping, cracking, separating, etc. Among other problems, such eventscan result in fluid leakage and poor adhesion as well as malfunctioningof the micro-fluid ejection heads, such as misdirected nozzles.Moreover, attempts to make adhesive materials more flexible after curingoften lead to adhesive materials that are less resistant to chemicaldegradation by the fluids being ejected.

Accordingly, a need exists for, amongst other things, a flexibleadhesive composition that is curable at relatively low temperatures andthat is suitable for use in assembling micro-fluid ejection headcomponents, and particularly, for attaching micro-fluid ejection headsto ejection device structures.

With regard to the foregoing and other object and advantages, variousembodiments of the disclosure provide a thermally curable adhesivecomposition for attaching a micro-fluid ejection head to a devicewherein the adhesive has a relatively low shear modulus upon curing.Various exemplary embodiments also provide a micro-fluid ejection headhaving an ejector chip and a thermally curable adhesive attachedthereto, the adhesive having a shear modulus of less than about 10 MPaat 25° C., wherein “MPa” stands for “MegaPascals” (i.e., 1.0×10⁶Pascals).

Additionally, embodiments provide a micro-fluid ejection device havingan ejector chip and a thermally curable adhesive attached thereto, theadhesive having a glass transition temperature of less than about 65° C.Various other embodiments provide a method for attaching a micro-fluidejection head to a device. One such method includes attaching the headto a device with a thermally curable adhesive with a relatively lowshear modulus dispensed between the head and the device, and curing theadhesive composition to provide the micro-fluid ejection device.

Advantages of the exemplary embodiments may include, but are not limitedto, a reduction in ejector chip substrate bow, an increase in ejectorhead durability, increased planarity of the ejector head, and the like.Other advantages might include the provision of adhesives havingimproved mechanical, adhesive, and ink resistive properties. Reducedstresses may be present in the ejector head substrates due to thepresence of improved adhesives according to the disclosed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the disclosed embodiments may becomeapparent by reference to the detailed description when considered inconjunction with the figures, which are not to scale, wherein likereference numbers indicate like elements through the several views, andwherein:

FIG. 1 is a perspective view of a micro-fluid ejection device accordingto an exemplary embodiment of the disclosure;

FIG. 2, is a perspective view, not to scale, of an ink jet printercapable of controlling a micro-fluid ejection device according to thedisclosure;

FIG. 3 is a cross-sectional view, not to scale, of a portion of amicro-fluid ejection device according to an embodiment of thedisclosure;

FIG. 4A is a cross-sectional view, not to scale, of a micro-fluidejection device incorporating one or more prior art adhesivecompositions; and

FIG. 4B is a cross-sectional cutaway side view, not to scale, of aportion of a micro-fluid ejection device according to an embodiment ofthe disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In general the disclosure is directed to describing improvedcompositions, structures, and methods related to thermally curableadhesives used to assemble component parts of micro-fluid ejectiondevices. More specifically, the improved adhesive compositions discussedherein might be used to, for example, reduce residual stresses that mayresult from heat-treating micro-fluid ejection heads to cure theadhesives.

In order to more fully disclose various embodiments of the invention,attention is directed to the following description of a representativemicro-fluid ejection device incorporating the improved thermally curableadhesive described herein. With reference to FIG. 1, there is shown, inperspective view, a micro-fluid ejection device 10 including one or moremicro-fluid ejection heads 12 attached to a head portion 14 of thedevice 10. A fluid reservoir 16 containing one or more fluids is fixedly(or removably) attached to the head portion 14 for feeding fluid to theone or more micro-fluid ejection heads 12 for ejection of fluid toward amedia or substrate from nozzles 18 on a nozzle plate 20. Although FIG. 1illustrates the fluid reservoir being directly attached to a headportion 14, other embodiments might attach a fluid reservoir indirectlyto a head portion, such as by tubing, for example. Each reservoir 16 maycontain a single fluid, such as a black, cyan, magenta or yellow ink ormay contain multiple fluids. In the illustration shown in FIG. 1, thedevice 10 has a single micro-fluid ejection head 12 for ejecting asingle fluid. However, the device 10 may contain two or more ejectionheads for ejecting two or more fluids, or a single ejection head 12 mayeject multiple fluids, or other variations on the same.

In order to control the ejection of fluid from the nozzles 18, each ofthe micro-fluid ejection heads 12 is usually electrically connected to acontroller in an ejection control device, such as, for example, aprinter 21 (FIG. 2), to which the device 10 is attached. In theillustrated embodiment, connections between the controller and thedevice 10 are provided by contact pads 22 which are disposed on a firstportion 24 of a flexible circuit 26. An exemplary flexible circuit 26 isformed from a resilient polymeric film, such as a polyimide film, whichhas conductive traces 28 thereon for conducting electrical signals froma source to the ejection head 12 connected to the traces 28 of theflexible circuit 26. A second portion 30 of the flexible circuit 26 istypically disposed on an operative side 32 of the head portion 14. Thereverse side of the flexible circuit 26 typically contains the traces 28which provide electrical continuity between the contact pads 22 and themicro-fluid ejection heads 12 for controlling the ejection of fluid fromthe micro-fluid ejection heads 12. TAB bond or wire bond connections,for example, are made between the traces 28 and each individualmicro-fluid ejection head 12 as described in more detail below.

Exemplary connections between a flexible circuit and a micro-fluidejection head are shown in detail by reference to FIG. 3. As describedabove, flexible circuits 26 contain traces 28 which are electricallyconnected to a substrate 34. The substrate 34 may be part of an ejectorchip having resistors and/or other actuators, such as piezoelectricdevices or MEMs devices for inducing ejection of fluid through nozzles18 of a nozzle plate 20 toward a print media. Connection pads 36 on theflexible circuits 26 are operatively connected to bond pads 38 on thesubstrate 34, such as by TAB bonding techniques or by use of wires 40using a wire bonding procedure through windows 42 and/or 44 in thecircuit 26 and/or nozzle plate 20.

As shown in FIG. 3, the substrate 34 is attached to the head portion 14,such as in a chip pocket 46. Prior to attaching the substrate 34 to thehead portion 14, a nozzle plate 20 may be adhesively attached to theejector chip using adhesive 48 (in another embodiment, a nozzle platemay be attached to the ejector chip by forming the nozzle plate on thesubstrate using photoimageable techniques). The assembly provided by thenozzle plate 20 attached to the substrate 34 is referred to herein asthe substrate/nozzle plate assembly 20/34 (FIG. 3). In some embodiments,the assembly 20/34 encompasses the micro-fluid ejection head itself.

The adhesive 48 may be a heat curable adhesive such a B-stageablethermal cure resins including, but not limited to phenolic resinsresorcinol resins, epoxy resins, ethylene-urea resins, furane resins,polyurethane resins and silicone resins. The adhesive 48 may be curedbefore attaching the substrate 34 to the head portion 14 and, in anexemplary embodiment, the adhesive 48 has a thickness ranging from about1 to about 25 microns.

After bonding the nozzle plate 20 and substrate 34 together, thesubstrate/nozzle plate assembly 20/34 may be attached to the headportion 14 in chip pocket 46 using a die bond adhesive 50. In variousembodiments of the disclosure, the die bond adhesive 50 used to connectthe substrate/nozzle plate assembly 20/34 to the head portion 14includes one or more adhesive components that make up a compositionhaving a relatively low shear modulus.

“Shear modulus” involves the relation of stress to strain according toHooke's Law as shown in Equation (1) as follows:(stress)=∥(strain)  (1)

In Equation (1) m represents a quantity often referred to as rigidity.When the relationship illustrated by Equation (1) is applied to a force“F” across a given area “A,” Equation (1) may be more specificallyrepresented by Equation (2) as follows:F/A=μ(ΔL/L)  (2)

In Equation (2) above, the variable “L” represents original length of anobject before said object was acted upon by force F. “ΔL” represents thechange in length occurring after force “F” has acted upon the object.Therefore, the rigidity (“μ”) of the object is a proportionalityconstant relating the pressure applied to an object with the ratiobetween the object change in length with the objects original length.

When Equation (2) and a given rigidity value “μ” are used to determineelastic properties of an object, Equation (3), shown below, is used toderive a shear modulus value from the rigidity m value determined inEquation (2). Equation (3) is shown below as follows:μ=E/2(L+v)  (3)In Equation (3) above, shear modulus is the proportional relationshipbetween rigidity “γ” and the right hand side of the equation, includingthe Poisson ratio “v” and Young's modulus “E.”

Applying Hooke's Law and elasticity theory to physical properties ofmicro-fluid ejection heads, reliable data may be established tocorrelate the elastic properties of adhesives with the effect of saidadhesives on one or more surfaces of a micro-fluid ejection head. Shearmodulus values are dependent on temperature, therefore, a given shearmodulus value for a given adhesive will be given in pressure units at aspecific temperature. Various embodiments of the disclosure includecompositions with shear modulus values of less than 10 MPa at 25° C. asdetermine by a rheometer from TA Instruments of New Castle, Del. underthe trade name ARES in a dynamic parallel plate configuration with afrequency of 1.0 rad/sec and a strain of 0.3% after the material iscured. In certain exemplary embodiments, one or more of the claimedcompositions have shear modulus values of less than about 1.0 MPa at 25°C.

With reference now to FIG. 4A, a cross-sectional view of a non-planarmicro-fluid ejection head 12 (e.g., substrate/nozzle plate assembly20/34) is illustrated. The substrate/nozzle plate assembly 20/34 isattached to a head portion 14 in a chip pocket 46. In the prior artejection head 12, the substrate/nozzle plate assembly 20/34 was attachedto the chip pocket 46 using a prior art die attach adhesive 58 having ashear modulus of substantially more than 10 MPa at 25° C. The non-planarcharacteristic of micro-fluid ejection head 12 is caused at least inpart by high temperature curing of the die attach adhesive 58.

The example shown in FIG. 4A is provided to illustrate certainundesirable effects of high temperature curing including non-planarmicro-fluid ejection head surfaces causing undesirable effects such as“chip bowing,” adhesive layer cracking, and increased overall fragilityof the micro-fluid ejection head 12 and substrate/nozzle plate assembly20/34. Chip bowing typically results from the substrate/nozzle plateassembly 20/34 and the head portion 14 having dissimilar coefficients ofthermal expansion, since the surface of the substrate/nozzle plateassembly 20/34 bonded to the head portion 14 most commonly is silicon orceramic and the portion 14 is, for example, typically a polymericmaterial such as a modified phenylene oxide. Thus, the adhesive 58should be flexible enough to accommodate both the dissimilar expansionsand contractions of the substrate chip/nozzle plate assembly 20/34 andthe head portion 14. Chip bowing may result in nozzles being misalignedor aligned at an undesired angle (often called “planarity” of nozzles),which may also diminish the quality of fluid ejected from the nozzles.

Chip fragility is believed to increase in severity because the adhesivelayer reaches its glass transition temperature (T_(g)) before thesubstrate/nozzle plate assembly 20/34 and head portion 14 have finishedcooling and contracting relative to one another after the curing of theadhesive layer 58, imparting stress onto the substrate/nozzle plateassembly. Accordingly, in an exemplary embodiment of the invention, anadhesive is used that has glass transition temperature below thetemperature to which the head portion 14 is cooled. For example, anadhesive with a glass transition temperature of less than about 65° C.,such as one having a glass transition temperature of less than about 50°C. or less than about 25° C. might be used in an exemplary embodiment.

The glass transition temperature of a material with elastic propertiesis the temperature at which the material transitions to more brittlephysical properties or more elastic physical properties, depending onwhether the temperature is decreasing or increasing, respectively. Aftercuring, as the adhesive layer 58 cools below its glass transitiontemperature, the adhesive 58 becomes significantly more brittle thanbefore reaching its glass transition temperature. If the adhesive 58 isstretched or compressed at a temperature below its glass transitiontemperature, the adhesive may crack or buckle. Therefore, usingadhesives with lower glass transition temperatures will decrease thechances of adhesive cracking or buckling. Similarly, considering thatshear modulus values directly relate to how brittle an adhesive will beat a given temperature, adhesives having lower shear modulus values aremore flexible at lower temperatures, thereby decreasing the likelihoodof adhesive cracking or buckling. Adhesive layer cracking may result ina compromised fluid seal, whereby micro-fluid ejection fluid leaks fromthe substrate/nozzle plate assembly 20/34 might cause undesirabledeposits of fluid, and/or corrosion of electrical components.

High curing temperatures may also cause increased fragility. Adhesiveshaving lower shear modulus values and lower glass transitiontemperatures may be cured with lower temperatures thereby, decreasingthe chances for micro-fluid ejection head fragility. Increased fragilityof micro-fluid ejection heads increases the chances for micro-fluidejection products becoming unfit for use due to shattering ofmicro-fluid ejections heads and other parts of the micro-fluid ejectiondevice.

In contrast to FIG. 4A, the head portion 14 shown in FIG. 4B illustratesa micro-fluid ejection head 12 comprising a substrate/nozzle plateassembly 20/34 that is attached to the chip pocket 46 using die attachadhesive 50 made of one or more of the compositions described herein.Using compositions such as that described below may result in decreasedchip bowing, decreased micro-fluid ejection head cracking, and/ordecreased fragility of micro-fluid ejection heads. Such improvedcharacteristics may be possible by the use of a die attach adhesivehaving a relatively low shear modulus. For the purposes of certainembodiments in this disclosure, “relatively low shear modulus” isdefined as a shear modulus at least lower than about 10 MPa at 25° C.“Relatively low shear modulus” may, however, be defined as a shearmodulus lower than about 1.0 MPa at 25° C. for certain exemplaryembodiments disclosed herein.

In an exemplary embodiment, die attach adhesive 50 is a compositionincluding (1) from about 50.0 to about 95.0 percent by weight of atleast one cross-linkable resin selected from the group of epoxy resins,siloxane resins, urethane resins, and functionalized olefin resins; (2)from about 0.1 to about 25.0 percent by weight of at least one thermalcurative agent selected from the group of imidazoles, amines, peroxides,organic accelerators, and sulfur; and (3) from about 0.0 to about 30.0percent by weight filler, wherein the composition exhibits a relativelylow shear modulus upon curing. In some variations of these exemplaryembodiments, the adhesive 50 may include from about 0.0 to about 10.0percent by weight silane coupling agent. In the embodiments describedabove, the filler may include from about 0.0 to about 30.0 percent byweight titanium dioxide, and from about 0.0 to about 30.0 percent byweight fumed silica or another filler component such as clay orfunctionalized clay, silica, talc, carbon black, carbon fibers.

More specific exemplary embodiments of the composition of adhesive 50are listed in Tables 1 through Table 7 below. TABLE 1 (Composition 1)Concentration Material (percent by weight) Trade name Supplier Flexibleepoxy 37.8 GE-35 CVC resin Aliphatic flexible 37.8 Epalloy 3-23 CVCepoxy resin Bisphenol M 8.4 Bisphenol M Aldrich Imidazole catalyst 9.5Curezol-17-Z Air Products Epoxy silane 0.2 A-187 GE Silicones Titaniumdioxide 4.2 Ti-Pure R-900 DuPont Fumed Silica 2.1 TS-720 Cabot

As shown above, composition 1 includes from about 25.0 to about 50.0percent by weight multi-functional epoxy resin; from about 25.0 to about50.0 percent by weight aliphatic di-functional epoxy resin; and fromabout 0.1 to about 15.0 percent by weight phenolic cross-linking agent.The composition also includes from about 0.1 to about 20.0 percent byweight of an imidazole catalyst and from about 0.0 to about 30.0 weightpercent fillers. As shown in Table 8, Composition 1 has a relatively lowshear modulus value of about 0.225 MPa at 25° C. and a low glasstransition temperature of about 10.5° C.

There are a number of epoxy resins, curing agents, and fillers availablefor application with various embodiments of the invention. In the firstcomposition illustrated in Table 1, an exemplary multi-functional epoxyresin is available from CVC Specialty Chemicals, Inc. under the tradename ERISYS GE-35. An exemplary aliphatic di-functional epoxy resin isavailable from CVC Specialty Chemicals, Inc. under the trade nameEPALLOY 3-23. A suitable phenolic cross-linking agent is available fromSignna Aldrichl Company under the trade designation Bisphenol M. Auseful curing agent is available from Air Products and Chemicals, Inc.under the trade name CUREZOL C17Z. A suitable epoxy silane couplingagent is available from GE Advanced Materials, Silicones of Wilton,Conn. under the trade name SILQUEST A-187 SILANE. Suitable fillers suchas titanium dioxide, and fumed silica are available from a number ofdifferent suppliers. For example, titanium dioxide is available fromDuPont Titanium Technologies under the trade name TI-PURE R-900 andfumed silica is available from Cabot Corporation of Boston, Mass. underthe trade name CAB-O-SILTS-720. TABLE 2 (Composition 2) ConcentrationMaterial (percent by weight) Trade name Supplier Diphenyl siloxane 79.5PMS-E15 Gelest Tetraethylene- 7.7 TEPA Air Products pentamine EpoxySilane 0.9 A-187 GE Silicones Titanium dioxide 4.0 Ti-Pure R-900 DupontFumed Silica 7.9 TS-720 Cabot

In Table 2, composition 2, includes from about 50.0 to about 95.0percent by weight diphenyl siloxane resin, from about 0.1 to about 20.0percent by weight of tetraethylenepentamine, and from about 0.0 to about10.0 percent by weight epoxy silane. The fillers include from about 0.0to about 30.0 percent by weight titanium dioxide; and from about 0.0 toabout 30.0 percent by weight fumed silica. As shown in Table 8,Composition 2 has a relatively low shear modulus value of about 1.98 MPaat 25° C. and a low glass transition temperature of about −11.2° C.

In accordance with the foregoing composition, a suitable diphenylsiloxane resin is available from Gelest, Inc. of Morrisville, Pa. underthe trade name PMS E-15. A useful tetraethylenepentamine curing agentfor this composition is available from Air Products or Sigma AldrichCompany under the trade designation TEPA (Tetraethylenepentamine). TABLE3 (Composition 3) Concentration Material (percent by weight) Trade nameSupplier Flexible epoxy 19.9 GE-35 CVC resin Epoxy siloxane 19.9SIB1115.0 Gelest Carboxyl-terminated 39.7 2000X162 Noveon butadieneAmine adduct 10.7 Ancamine 2337 Air Products Epoxy Silane 0.2 A-187 GESilicones Titanium dioxide 4.0 Ti-Pure R-900 Dupont Fumed Silica 5.6TS-720 Cabot

Table 3 illustrates yet another exemplary adhesive composition.Composition 3 includes from about 0.0 to about 50.0 percent by weightmulti-functional epoxy resin; from about 0.0 to about 50.0 percent byweight epoxy siloxane resin; from about 0.0 to about 90.0 percent byweight carboxyl-terminated butadiene; and from about 0.1 to about 20.0percent by weight of an amine adduct thermal curative agent. Thisembodiment also includes from about 0.0 to about 15.0 percent by weightepoxy silane, from about 0.0 to about 30.0 percent by weight titaniumdioxide, and from about 0.0 to about 30.0 percent by weight fumedsilica. As shown in Table 8, Composition 3 has a substantially low shearmodulus value of about 0.175 MPa at 25° C. and a low glass transitiontemperature of about −6.7° C.

In accordance with the foregoing composition, the epoxy siloxane thatmay be used is available from Gelest, Inc. is under the tradedesignation SIB115.0. The carboxyl-terminated butadiene that may be usedis available from Noveon Specialty Chemicals of Cleveland, Ohio underthe trade name HYCAR CTB 2000X162. A suitable curing agent in the formof an amine adduct is available from Air Products and Chemicals, Inc.under the trade name ANCAMINE 2337S. TABLE 4 (Composition 4)Concentration Material (percent by weight) Trade name SupplierEpoxidized 36.2 Poly BD 600E Sartomer butadiene resin Anhydride 50.7130-MA-8 Sartomer functional butadiene Anhydride cross 6.1 MHHPA Miller-linker Stephenson Azine imidazole 2.3 2MZ-Azine Air Products EpoxySilane 0.4 A-187 GE Silicones Titanium dioxide 2.0 Ti-Pure R-900 DuPontFumed Silica 2.3 TS-720 CabotAs provided in Table 4, Composition 4 includes from about 0.0 to about50.0 percent by weight epoxidized butadiene resin; from about 0.0 toabout 75.0 percent by weight anhydride functional butadiene; from about0.1 to about 20.0 percent by weight anhydride cross-linking agent; andfrom about 0.1 to about 20.0 percent by weight of an azine imidazolethermal curative agent. From about 0.0 to about 15.0 percent by weightepoxy silane; from about 0.0 to about 30.0 percent by weight titaniumdioxide, and from about 0.0 to about 30.0 percent by weight fumed silicaare also included in the composition. As shown in Table 8, Composition 4has a considerably lower shear modulus value of about 0.151 MPa at 25°C. and a considerably lower glass transition temperature of about −30°C.

For composition 4, a suitable epoxidized butadiene resin is availablefrom Sartomer Company, Inc. of Exton, Pa. under the trade name POLY BD600E. A suitable anhydride functional butadiene resin that may be usedis available from Sartomer Company, Inc. of Exton, Pa. under the tradename RICON 130MA8. The cross-linking agent that may be used is availablefrom Miller-Stephenson Chemical Company, Inc. under the tradedesignation Anhydride MHHPA. A suitable curing agent is an azineimidazole that is available from Air Products and Chemicals, Inc. underthe trade name CUREZOL® 2MZ Azine. TABLE 5 (Composition 5) ConcentrationMaterial (percent by weight) Trade name Supplier Methacrylated 86.0Riacryl 3100 Sartomer butadiene resin Peroxide catalyst 2.8 Luperox LPAldrich Epoxy Silane 0.9 A-187 GE Silicones Titanium dioxide 4.3 Ti-PureR-900 Dupont Fumed Silica 6.0 TS-720 Cabot

As provided in Table 5 Composition 5 includes from about 50.0 to about95.0 percent by weight methacrylated butadiene resin, and from about 0.1to about 30.0 percent by weight of peroxide catalyst thermal curativeagent, A suitable methacrylated butadiene resin is available fromSartomer Company, Inc. of Exton, Pa. under the trade name RICACRYIL3100. The curing agent is suitably a peroxide catalyst available fromSigma Aldrich Company under the trade name LUPEROX LP. As shown in Table8, Composition 5 has a low shear modulus value of about 0.74 MPa at 25°C. and a considerably lower glass transition temperature of less than−60° C. TABLE 6 (Composition 6) Concentration Material (percent byweight) Trade name Supplier Flexible epoxy 73.6-88.0 EXA-4850 Dainipponresin Ink Bisphenol M   0-8.4 Bisphenol M Aldrich Imidazole  9.2-11.0CUREZOL-17-Z Air Products catalyst Epoxy Silane 0.8-1.0 A-187 GESilicones Amine adduct   0-4.1 ANCAMINE 2337 Air Products Fumed Silica  0-4.1 TS-720 Cabot

As provided in Table 6, Composition 6 includes from about 50.0 to about95.0 percent by weight flexible epoxy resin, from about 0.0 to about 30percent by weight bisphenol-M, and from about 0.1 to about 20.0 percentby weight of imidazole catayst thennal curative agent. A suitableflexible epoxy resin is available from Dainippon Ink and Chemicals, Inc.of Tokyo, Japan under the trade name EPICLON EXA-4850. As shown in Table8, Composition 6 has a low shear modulus value ranging from about 1.75to about 4.4 MPa at 25° C. and a glass transition temperature rangingfrom about 20 to about 31° C. TABLE 7 (Composition 7) ConcentrationMaterial (percent by weight) Trade name Supplier Flexible epoxy55.0-88.0 EXA-4850 Dainippon resin Ink Bisphenol-F   0-27.0 830-LVPDainippon Ink Imidazole  7.4-11.0 CUREZOL-17-Z Air Products catalystEpoxy Silane 0.6-1.0 A-187 GE Silicones Amine adduct   0-3.5 ANCAMINE2337 Air Products Fumed Silica   0-3.5 TS-720 Cabot

As provided in Table 7, Composition 7 includes from about 50.0 to about95.0 percent by weight flexible epoxy resin, from about 0 to about 50percent by weight bisphenol-F, from about 0.1 to about 20.0 percent byweight of imidazole catalyst thermal curative agent, from about 0.1 toabout 20 percent by weight epoxy silane coupling agent, from about 0 toabout 20 percent by weight of amine adduct, and from about 0 to about 30percent by weight fumed silica. As shown in Table 8, Composition 7 has alow shear modulus value ranging from about 3.9 to about 8.7 MPa at 25°C. and a glass transition temperature ranging from about 27 to about 60°C.

A comparison of the shear modulus and glass transition temperatureproperties of the Compositions 1-7 compared to a conventional die bondadhesive available from Emerson & Cuming of Monroe Townships N.J. underthe trade name ECCOBOND 3193-17 are provided in Table 8. TABLE 8 ShearModulus Sample (MPa) (25° C.) Tg (° C.) Eccobond 3193-17 15.4 92.3Composition 1 0.225 10.5 Composition 2 1.98 −11.2 Composition 3 0.175−6.7 Composition 4 0.151 −30 Composition 5 0.74 <−60 Composition 61.75-4.4  20-31 Composition 7 3.9-8.72 27.7-60  

As illustrated in Table 8, the ECCOBOND 3193-17 adhesive has arelatively high shear modulus value of 15.4 MPa at 25° C. as compared tothe shear modulus values of the Compositions 1-7 which are all less than10 MPa at 25° C. Similarly, the ECCOBOND 3193-17 has a relatively highglass transition temperature of 92.3° C. compared to the much lowervalues of the compositions 1-7 which are all less than 65° C. In otherwords, ECCOBOND 3193-17 becomes significantly more rigid when it coolsto about 92° C., whereas Compositions 1-7 do not become significantlymore rigid until cooling to at least about 65° C.

Various embodiments of the invention are also directed to a micro-fluidejection device including a substrate/nozzle plate assembly and athermally curable adhesive attached thereto, the adhesive having a shearmodulus of less than about 10.0 MPa at 25° C. In one particularembodiment, shown in FIG. 4B, a substrate/nozzle plate assembly 20/34 isattached to head portion 14 by a die attach adhesive 50 made accordingto Composition 1 above. In a related embodiment, a substrate chip/nozzleplate assembly 20/34 is attached to a head portion by a die attachadhesive made according to Composition 2 above. In yet otherembodiments, micro-fluid ejection heads are attached to head portions bydie attach adhesives made according to Compositions 3, 4 and 5 abovehaving a relatively low shear modulus values at 25° C. and having glasstransition temperatures of less than about 65° C.

It is contemplated, and will be apparent to those skilled in the artfrom the preceding description and the accompanying drawings thatmodifications and/or changes may be made to the embodiments of thedisclosure. Accordingly, it is expressly intended that the foregoingdescription and the accompanying drawings are illustrative of exemplaryembodiments only, not limiting thereto, and that the true spirit andscope of the present disclosure be determined by reference to theappended claims.

1. A thermally curable adhesive composition for attaching a micro-fluidejection head to a device, the adhesive comprising a. from about 50.0 toabout 95.0 percent by weight of at least one cross-linkable resinselected from the group consisting of epoxy resins, siloxane resins,urethane resins, and functionalized olefin resins; b. from about 0.1 toabout 25.0 percent by weight of at least one thermal curative agent; andc. from about 0.0 to about 30.0 percent by weight filler, wherein thecomposition exhibits a relatively low shear modulus upon curing.
 2. Theadhesive composition of claim 1 wherein the at least one thermalcurative agent comprises a curative agent selected from the groupconsisting of imidazoles, amines, peroxides, organic accelerators, andsulfur.
 3. The adhesive composition of claim 1, further comprising fromabout 0.1 to about 10.0 percent by weight silane coupling agent.
 4. Theadhesive composition of claim 1, wherein the filler further comprises a.from about 0.0 to about 20.0 percent by weight epoxy silane; b. fromabout 0.0 to about 30.0 percent by weight titanium dioxide; and c. fromabout 0.0 to about 30.0 percent by weight fumed silica.
 5. The adhesivecomposition of claim 1, wherein the adhesive composition comprises a.from about 36.0 to about 39.0 percent by weight multi-functional epoxyresin; b. from about 36.0 to about 39.0 percent by weight aliphaticdi-functional epoxy resin; c. from about 7.0 to about 10.0 percent byweight phenolic cross-linking agent; and d. from about 7.0 to about 12.0percent by weight of at least one thermal curative agent.
 6. Theadhesive composition of claim 5, wherein the at least one thennalcurative agent comprises an imidazole catalyst.
 7. The adhesivecomposition of claim 6, further comprising from about 0.1 to about 10.0percent by weight silane coupling agent.
 8. The adhesive composition ofclaim 7, further comprising a. from about 0.0 to about 30.0 percent byweight titanium dioxide; and b. from about 0.0 to about 30.0 percent byweight fumed silica.
 9. The adhesive composition of claim 1, wherein theadhesive composition comprises a. from about 77.0 to about 82.0 percentby weight diphenyl siloxane resin, and b. from about 5.0 to about 10.0percent by weight of at least one thermal curative agent.
 10. Theadhesive composition of claim 9, wherein the at least one thermalcurative agent comprises tetraethylenepentamine.
 11. The adhesivecomposition of claim 10, further comprising from about 0.1 to about 10.0percent by weight silane coupling agent.
 12. The adhesive composition ofclaim 11, further comprising a. from about 0.0 to about 30.0 percent byweight titanium dioxide; and b. from about 0.0 to about 30.0 percent byweight fumed silica.
 13. The adhesive composition of claim 1, whereinthe adhesive composition comprises a. from about 18.0 to about 22.0percent by weight multi-functional epoxy resin; b. from about 18.0 toabout 22.0 percent by weight epoxy siloxane resin; c. from about 38.0 toabout 42.0 percent by weight carboxyl terminated butadiene; and d. fromabout 9.0 to about 13.0 percent by weight of at least one thermalcurative agent.
 14. The adhesive composition of claim 13, wherein the atleast one thermal curative agent comprises amine adduct.
 15. Theadhesive composition of claim 14, further comprising from about 0.1 toabout 10.0 percent by weight silane coupling agent.
 16. The adhesivecomposition of claim 15, further comprising a. from about 0.0 to about30.0 percent by weight titanium dioxide; and b. from about 0.0 to about30.0 percent by weight fumed silica.
 17. The adhesive composition ofclaim 1, wherein the adhesive composition comprises a. from about 1.0 toabout 50.0 percent by weight epoxidized butadiene resin; b. from about1.0 to about 75.0 percent by weight anhydride functional butadiene; c.from about 0.1 to about 20.0 percent by weight anhydride cross-linkingagent; and d. from about 0.1 to about 20.0 percent by weight of at leastone thermal curative agent.
 18. The adhesive composition of claim 17,wherein the at least one thermal curative agent comprises azineimidazole.
 19. The adhesive composition of claim 18, further comprisingfrom about 0.1 to about 10.0 percent by weight silane coupling agent.20. The adhesive composition of claim 19, further comprising a. fromabout 0.0 to about 30.0 percent by weight titanium dioxide; and b. fromabout 0.0 to about 30.0 percent by weight fumed silica.
 21. The adhesivecomposition of claim 1, wherein the adhesive composition comprises a.from about 50.0 to about 95.0 percent by weight methacrylated butadieneresin, and b. from about 0.1 to about 15.0 percent by weight of at leastone thermal curative agent.
 22. The adhesive composition of claim 21,wherein the at least one thennal curative agent comprises peroxidecatalyst.
 23. The adhesive composition of claim 22, further comprisingfrom about 0.1 to about 10.0 percent by weight silane coupling agent.24. The adhesive composition of claim 23, further comprising a. fromabout 0.0 to about 30.0 percent by weight titanium dioxide; and b. fromabout 0.0 to about 30.0 percent by weight fumed silica.
 25. Amicro-fluid ejection device comprising an ejector chip and a thermallycurable adhesive attached thereto, the adhesive having a shear modulusof less than about 10.0 MPa at 25° C.
 26. The micro-fluid ejectiondevice of claim 25, wherein the adhesive comprises an adhesive having ashear modulus of less than about 3.0 MPa at 25° C.
 27. The micro-fluidejection device of claim 25, wherein the adhesive comprises an adhesivehaving a shear modulus of less than about 1.0 MPa at 25° C.
 28. Amicro-fluid ejection device comprising an ejector chip and a thermallycurable adhesive attached thereto, the adhesive having a glasstransition temperature of less than about 65° C.
 29. The micro-fluidejection device of claim 28, wherein the adhesive comprises an adhesivehaving a glass transition temperature of less than about 50° C.
 30. Themicro-fluid ejection device of claim 28, wherein the adhesive comprisesan adhesive having a glass transition temperature of less than about at25° C.
 31. A method for attaching a micro-fluid ejection head to adevice comprising: a. attaching a micro-fluid ejection head to a devicewith a thermally curable adhesive disposed between the ejection head andthe device, the thermally curable adhesive composition comprising i.from about 50.0 to about 95.0 percent by weight of at least onecross-linkable resin selected from the group consisting of epoxy resins,siloxane resins, urethane resins, and functionalized olefin resins, ii.from about 0.0 to about 25.0 percent by weight of at least one thermalcurative agent; and iii. from about 0.0 to about 30.0 percent by weightfiller, wherein the composition exhibits a relatively low shear modulusupon curing; and b. curing the adhesive composition to provide amicro-fluid ejection device.
 32. The method of claim 31 wherein theadhesive composition comprises a mixture having a shear modulus of lessthan 10.0 MPa at 25° C.
 33. The method of claim 31 wherein the adhesivecomposition comprises a mixture having a shear modulus of less than 3.0MPa at 25° C.
 34. The method of claim 31 wherein the adhesivecomposition comprises a mixture having a shear modulus of less than 1.0MPa at 25° C.
 35. The method of claim 31 wherein the adhesivecomposition comprises a mixture having a glass transition temperature ofless than 65° C.
 36. The method of claim 31 wherein the adhesivecomposition comprises a mixture having a glass transition temperature ofless than 25° C.